In-situ characterization of initial marine corrosion induced by rare-earth elements modified inclusions in Zr-Ti deoxidized low-alloy steels
In-situ characterization of initial marine corrosion induced by rare-earth elements modified inclusions in Zr-Ti deoxidized low-alloy steels
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DOI：
10.1016/j.jmrt.2019.11.080
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发表时间：
2020-03
期刊：
影响因子：
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通讯作者：
Wenzhui Wei;W. Kaiming;Xian Zhang;Jing Liu;P. Qiu;Lin Cheng
中科院分区：
文献类型：
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作者：
Wenzhui Wei;W. Kaiming;Xian Zhang;Jing Liu;P. Qiu;Lin Cheng
采用第一性原理模型，结合原位扫描振动电极技术（SVET）、扫描电子显微镜/X射线能谱（SEM/EDS）和共焦拉曼显微镜（CRM）等分析方法，研究了稀土（RE）改性夹杂物对Zr-Ti脱氧低合金钢初始海洋腐蚀的影响。结果表明，在该合金中形成了两种复杂的夹杂物，夹杂物中夹杂物的成分分别为RExZryOz-RE 2 O2 S和RExZryOz-RE 2 O2 S-TiN。RE 2 O2 S优先溶解在0.5wt%NaCl溶液中，而RExZryOz的溶解从外围扩展到中间的夹杂物，随后，在钢表面上形成稳定的凹坑。TiN在海洋环境中是稳定的，并最终从基底上脱离。原位SVET结果表明，单个和多个夹杂物对腐蚀过程中局部电流密度的变化均有影响，表明夹杂物的溶解促进了点蚀电化学活动，进而抑制了局部腐蚀的发展。此外，夹杂物和铁基体的腐蚀趋势进行了第一性原理模拟。最后，提出了两个示意性的模型来演示夹杂物对低合金钢的初始海洋腐蚀的影响。
In the present research, the effects of rare-earth (RE) elements modified inclusions on initial marine corrosion of Zr-Ti deoxidized low-alloy steels were studied by first principle modeling and a variety of analytical methods including in-situ scanning vibrating electrode technique (SVET), scanning electron microscopy with x-ray microanalysis (SEM/EDS), and confocal Raman microscopy (CRM). The obtained results revealed that two types of complex inclusions with intertwined components of RExZryOz-RE2O2S and RExZryOz-RE2O2S-TiN were formed. RE2O2S preferentially dissolved in 0.5 wt% NaCl solution, whereas the dissolution of RExZryOzpropagated from the periphery to the middle of the inclusions and subsequently, formed stable pits on the steel surface. TiN was stable in the marine environment and finally, became detached from the substrate. Moreover, in-situ SVET results demonstrated the local current density change during corrosion process was influenced by single and multiple inclusions, indicating that the dissolution of inclusions induced the electrochemical activities of pitting corrosion and further inhibited the propagation of local corrosion. Furthermore, the corrosion tendency of inclusions and the Fe matrix was examined by first principle modeling. Finally, two schematic models were proposed to demonstrate the effects of inclusions on initial marine corrosion of low-alloy steels.